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Updates to model-data comparisons

Filed under: — gavin @ 28 December 2009 - (Italian)

It’s worth going back every so often to see how projections made back in the day are shaping up. As we get to the end of another year, we can update all of the graphs of annual means with another single datapoint. Statistically this isn’t hugely important, but people seem interested, so why not?

For example, here is an update of the graph showing the annual mean anomalies from the IPCC AR4 models plotted against the surface temperature records from the HadCRUT3v and GISTEMP products (it really doesn’t matter which). Everything has been baselined to 1980-1999 (as in the 2007 IPCC report) and the envelope in grey encloses 95% of the model runs. The 2009 number is the Jan-Nov average.

As you can see, now that we have come out of the recent La Niña-induced slump, temperatures are back in the middle of the model estimates. If the current El Niño event continues into the spring, we can expect 2010 to be warmer still. But note, as always, that short term (15 years or less) trends are not usefully predictable as a function of the forcings. It’s worth pointing out as well, that the AR4 model simulations are an ‘ensemble of opportunity’ and vary substantially among themselves with the forcings imposed, the magnitude of the internal variability and of course, the sensitivity. Thus while they do span a large range of possible situations, the average of these simulations is not ‘truth’.

There is a claim doing the rounds that ‘no model’ can explain the recent variations in global mean temperature (George Will made the claim last month for instance). Of course, taken absolutely literally this must be true. No climate model simulation can match the exact timing of the internal variability in the climate years later. But something more is being implied, specifically, that no model produced any realisation of the internal variability that gave short term trends similar to what we’ve seen. And that is simply not true.

We can break it down a little more clearly. The trend in the annual mean HadCRUT3v data from 1998-2009 (assuming the year-to-date is a good estimate of the eventual value) is 0.06+/-0.14 ºC/dec (note this is positive!). If you want a negative (albeit non-significant) trend, then you could pick 2002-2009 in the GISTEMP record which is -0.04+/-0.23 ºC/dec. The range of trends in the model simulations for these two time periods are [-0.08,0.51] and [-0.14, 0.55], and in each case there are multiple model runs that have a lower trend than observed (5 simulations in both cases). Thus ‘a model’ did show a trend consistent with the current ‘pause’. However, that these models showed it, is just coincidence and one shouldn’t assume that these models are better than the others. Had the real world ‘pause’ happened at another time, different models would have had the closest match.

Another figure worth updating is the comparison of the ocean heat content (OHC) changes in the models compared to the latest data from NODC. Unfortunately, I don’t have the post-2003 model output handy, but the comparison between the 3-monthly data (to the end of Sep) and annual data versus the model output is still useful.


Update (May 2012): The graph has been corrected for a scaling error in the model output. Unfortunately, I don’t have a copy of the observational data exactly as it was at the time the original figure was made, and so the corrected version uses only the annual data from a slightly earlier point. The original figure is still available here.

(Note, that I’m not quite sure how this comparison should be baselined. The models are simply the difference from the control, while the observations are ‘as is’ from NOAA). I have linearly extended the ensemble mean model values for the post 2003 period (using a regression from 1993-2002) to get a rough sense of where those runs could have gone.

And finally, let’s revisit the oldest GCM projection of all, Hansen et al (1988). The Scenario B in that paper is running a little high compared with the actual forcings growth (by about 10%), and the old GISS model had a climate sensitivity that was a little higher (4.2ºC for a doubling of CO2) than the current best estimate (~3ºC).

The trends are probably most useful to think about, and for the period 1984 to 2009 (the 1984 date chosen because that is when these projections started), scenario B has a trend of 0.26+/-0.05 ºC/dec (95% uncertainties, no correction for auto-correlation). For the GISTEMP and HadCRUT3 data (assuming that the 2009 estimate is ok), the trends are 0.19+/-0.05 ºC/dec (note that the GISTEMP met-station index has 0.21+/-0.06 ºC/dec). Corrections for auto-correlation would make the uncertainties larger, but as it stands, the difference between the trends is just about significant.

Thus, it seems that the Hansen et al ‘B’ projection is likely running a little warm compared to the real world, but assuming (a little recklessly) that the 26 yr trend scales linearly with the sensitivity and the forcing, we could use this mismatch to estimate a sensitivity for the real world. That would give us 4.2/(0.26*0.9) * 0.19=~ 3.4 ºC. Of course, the error bars are quite large (I estimate about +/-1ºC due to uncertainty in the true underlying trends and the true forcings), but it’s interesting to note that the best estimate sensitivity deduced from this projection, is very close to what we think in any case. For reference, the trends in the AR4 models for the same period have a range 0.21+/-0.16 ºC/dec (95%). Note too, that the Hansen et al projection had very clear skill compared to a null hypothesis of no further warming.

The sharp-eyed among you might notice a couple of differences between the variance in the AR4 models in the first graph, and the Hansen et al model in the last. This is a real feature. The model used in the mid-1980s had a very simple representation of the ocean – it simply allowed the temperatures in the mixed layer to change based on the changing the fluxes at the surface. It did not contain any dynamic ocean variability – no El Niño events, no Atlantic multidecadal variability etc. and thus the variance from year to year was less than one would expect. Models today have dynamic ocean components and more ocean variability of various sorts, and I think that is clearly closer to reality than the 1980s vintage models, but the large variation in simulated variability still implies that there is some way to go.

So to conclude, despite the fact these are relatively crude metrics against which to judge the models, and there is a substantial degree of unforced variability, the matches to observations are still pretty good, and we are getting to the point where a better winnowing of models dependent on their skill may soon be possible. But more on that in the New Year.


906 Responses to “Updates to model-data comparisons”

  1. 751
    Completely Fed Up says:

    “744
    Tilo Reber says:
    6 January 2010 at 12:36 PM

    Barton:
    Going up or going down, Tilo? Or staying the same?

    That’s a lot of wasted space, Barton;”

    Which is called “dodging the question”.

    Note: there is no actual space on the internet. So it isn’t wasted.

    “See my response to Didactylos to see what I am claiming.”

    He didn’t ask what you were claiming. He asked “up, down or steady”.

    Which is it?

  2. 752
    Doug Bostrom says:

    “If you go back and look you will see that I asked Gavin to update his ENSO corrected HadCrut3 and failing that to give me the algorithm so that I could do it myself. And I offered to share the results, regardless of what they were.”

    How’s that going? Assuming Gavin is not going to do the work for you, that is?

  3. 753
    Doug Bostrom says:

    “My argument is that the thinning claims are difficult to believe without a corresponding shrinkage of sea ice area.”

    Why not go to “the thinning claims” and identify how they’re wrong?

    In any case, unless you’re completely blind or just plain obdurate, you can see that ice extent has been shrinking, so your fundamental premise appears pretty stupid. You’re arguing for something that is plainly not in evidence.

    Meanwhile, since you’re so demanding, here’s a demand in turn: you speculate that the multi-decade decline in extent may have arrested itself. How? Why?

    What a waste of disk space this has become.

  4. 754
    Susan says:

    Barton Paul,
    I’m not Tilo, but from other charts I’ve seen, 2009 sea ice coverage looked a lot like 2004-2005. Given the uncertainties in deriving the numbers you’ve provided by the university of illinois( the university certainly wasn’t collecting data on sea ice extent in 1870 or the earlier 1900’s was it, and to the same precision as satellite data?) Isn’t it safest scientifically speaking to say “Staying the same”?

  5. 755

    Tilo @ 666:

    Before you go off on the shortness of the period, remember that I also said this in 628. “But the recent stabilization of the Arctic and Antartic sea ice area makes me think that we may be right on the border of how much melt we are going to get – at least at this temperature. I think we’ll need a few more years to be sure. ”

    I’d suggest you plot peaks-to-peaks and troughs-to-troughs and see what that tells you. What it should tell you is that we’re losing ice extent on a trending-downwards cycle. Part of why I’m confident that 2010 will see an increase in minimum extend (more ice at the bottom, not more non-ice) this year is because there’s a solid track record of a multi-year recovery to a near-term high after a record low, followed by a return to the decline, a fresh record low, not-quite-complete-recovery, new low, etc.

    So … 2010 will have some “recovery”, but at some point in the future, 2010 will be above any other year’s recovery. Unless we quit it with all this CO2 stuff.

    Also, get all excited about increases in Antarctic ice really doesn’t bode well. The north and south poles are not equivalent. Yes, they are cold, but one is LAND and the other is SEA.

  6. 756
    davidmhoffer says:

    Since the original topic was revisiting models I did just that. I was looking at Aono/Amoto 1994 temperature reconstruction for Kyoto which was one of the first hockey stick graphs. It has a very accidental… but huge… error that totaly skews the graph. I would love to get in touch with Aono to discuss. In the meantime I’ve posted an analysis and corrected reconstruction here http://knowledgedrift.wordpress.com/category/knowledge-drift-and-the-climate-debate-how-ancient-calendars-caused-global-warming/

    [Response: Interesting, but unfortunately you are almost certainly wrong. The Gregorian calendar didn’t reach Japan until 1873 and previously they would have used there own luni-solar dates based on old Chinese calendars. The authors must therefore have had to have conversant in the translations between calanders and your supposition that they weren’t is not supportable without some actual evidence. – gavin]

  7. 757
    Doug Bostrom says:

    FurryCatHerder says: 6 January 2010 at 3:31 PM

    “So … 2010 will have some “recovery”, but at some point in the future, 2010 will be above any other year’s recovery.”

    That’s it, in a nutshell, as brief scrutiny of data reveals.

    “Also, get all excited about increases in Antarctic ice really doesn’t bode well.”

    Hah! Another isolated “weather” observation, but they just found Mawson’s ill-fated aircraft in Antarctica. Left on the ice in 1914, still on the ice in 1931, still there in 1975, now just discovered at low tide where it was sitting on the bottom having apparently been dropped by the ice at some point. Moment of discovery:

    “Tony Stewart, the [Australian expedition] field leader, said: “The carpenter just ambled in and said, ‘I think I might have found the air tractor,’ like he’d just picked up a newspaper at the local store. You haven’t seen us move so quickly in a long time.”

    “It was part of the fuselage of the historic plane, exposed by a blue moon (the second full moon in a calendar month), the lowest tide ever recorded at that site and an unprecedented melting of ice.”

    Is it weather, or climate? Interesting story, in any case:

    http://www.independent.co.uk/news/world/australasia/antarctics-first-plane-found-in-ice-1856789.html

  8. 758
    Didactylos says:

    I’m claiming that there was a slight recovery in the sea ice area since 2007.

    And that’s your problem. You don’t understand why this is ludicrous, in the same way you don’t understand why your other complaints don’t compute. There are countless explanations of why you are wrong, from me and many others. I’m not sure you bothered to read them all, but it is painfully clear that you don’t understand any of it.

    Should we continue to waste our time? You are clearly out of your depth. This isn’t your fault, but it would help if you could recognise the fact and stop trying to swim unaided.

    Ask for help. It is the only way to make progress.

    I want to say more, but I honestly don’t think you will pay any attention.

  9. 759
    Hank Roberts says:

    > Isn’t it safest scientifically speaking to say
    > “Staying the same”?

    Nope. If it were they would, but as it isn’t, they aren’t.

    You don’t need “brick moon” satellites from the 1800s or deep time to figure out when a polar sea was ice-covered; the animals and plants that live under ice make very different sediment layers than the animals and plants that live in open water, and sediment layers are well studied.

    http://www.google.com/search?q=sediment+core+ice+open+water

  10. 760
    dhogaza says:

    Stabilization of Arctic sea ice?

    Right on the 3% annual decline for extent…

  11. 761
    Didactylos says:

    Susan said:

    2009 sea ice coverage looked a lot like 2004-2005.

    It’s good that rational questions can come out of even the most pointless of discussions. Susan, with ice, just as with temperature, we need to look at a longer period than 5 years to see the trend. With just 5 data points, you will only see noise. They could be any value at all, and you would still be able to infer nothing from them.

    Fortunately, we have a lot more than 5 years. http://maps.grida.no/go/graphic/minimum-arctic-summer-sea-ice-extent

    So, Tilo wants to pretend there has been a “recovery” since 2007. That’s nonsense. After an extreme value like 2007, it is completely unsurprising that following values are closer to the trend line. If we called it a recovery after every minimum, then we would have a lot of recoveries!

  12. 762
    Matthew says:

    722, Greg C. Thank you for the programming tip. It confims my recent decision to start using Python. For I have Numerical
    Recipes in both Fortran and C.

  13. 763
    Hank Roberts says:

    PS for Susan, from the search I suggested above, these may be helpful. If you have been reading something that contradicts what you find here, please say where you read it.

    http://beyondpenguins.nsdl.org/issue/column.php?date=May2009&departmentid=field&columnid=field!researcher

    Mentions the author of the sea ice section of this report:
    http://www.climatescience.gov/Library/sap/sap1-2/final-report/

    There’s much more at that Google search and you can certainly improve on it; pick appropriate key words to add, and of course try Scholar

  14. 764
    Completely Fed Up says:

    Susan, have a look here:

    http://www.youtube.com/watch?v=2nruCRcbnY0

  15. 765
    davidmhoffer says:

    [Response: Interesting, but unfortunately you are almost certainly wrong. The Gregorian calendar didn’t reach Japan until 1873 and previously they would have used there own luni-solar dates based on old Chinese calendars

    PRECISELY! As the Gregorian calendar had been in use in Japan since before Aono/Amoto were born, they would not have been familiar with its history. Conversion from luni-solar dates would have relied on counting the number of days from the winter solstice, a methodology they would have developed in their initial research. As they worked backward in time using that method, they would not have known that the winter solstice that had occured on Dec 22 for the first 400 years of their data suddenly jumped to Dec 12 in 1582AD. They would have continued to use the same off set from the winter solstice that they had always used.

    If someone has a way to get in touch with the researchers (I have been trying) I would be eager to discuss with them. In the meantime, the corrected graph oscillates in tandem with the European MWA and LIA, suggesting that my correction is valid.

    [Response: This makes no logical sense. The conversion of the Japanese calendar to Gregorian has no relationship to the Julian calendar at all. Nothing special happens in 1583 and so your fix is meaningless. – gavin]

  16. 766
    davidmhoffer says:

    The point is that there WAS no Gregorian calendar to convert TO! It didnt START until Oct 15, 1582. The day before that was Oct 4, 1582. [edit]

    [Response: Now you are being ridiculous. The bloom date is being presented in the Gregorian calender consistently throughout the paper. You can convert any date from old-style or Japanese-style to a Gregorian calender date regardless of whether you are before or after 1583, or whether anyone in the world used that calendar at the time. – gavin]

  17. 767
    Hank Roberts says:

    Davidmhoffer: Google Scholar.

    http://scholar.google.com/scholar?sourceid=Mozilla-search&q=climatic+reconstruction+Japan+calendar

    finds, for instance:

    http://www.cfa.harvard.edu/~wsoon/MiyaharaHiroko08-d/AonoKazui07-Aug23-KyotoSpring.pdf

    [PDF] … of cherry tree flowering in Kyoto, Japan, and its application to reconstruction … Y Aono, K Kazui – International Journal of Climatology, 2008 – cfa.harvard.edu
    … Phenological data from the instrumental period were calibrated using springtime temperature observations, and then data from the historical period were used to reconstruct climate changes. … In this study, the dates, according to the Japanese lunar calendar, on which …

    Cited by 13:
    http://scholar.google.com/scholar?cites=3858062092740034921&hl=en&as_sdt=2000

  18. 768
    Doug Bostrom says:

    davidmhoffer says: 6 January 2010 at 7:30 PM

    Another eureka moment bites the dust. Still, it was an innovation and you should be proud of at least thinking of it.

  19. 769
    Bryan S says:

    Gavin,

    OK. The baselines are indeed slightly different in these two series.

    Let me go at this in a more precise way. The extrapolation of the GISS-ER ensemble mean shows an average estimated heat uptake of around 0.7X10^22 Joules per year from 1995 to present. However, when I use the Dominguez data up to 2003, then splice the Argo data since 2003 (adjusted for the baseline*) onto the end of the series, the rate of warming is only around 0.4X10^22 Joules per year (about the same as their long term increase since the 1960’s).

    [Response: I don’t think that is valid. There is considerable overlap in the period 2001 to 2005 as the Argo program ramped up and having that data assimilated consistently is important. You can’t simply graft on the anomaly from one analysis on to the other. I think we will just have to wait for the Domingues group to do that properly. – gavin]

    This rate of heat uptake is *considerably less* than the extrapolation of the GISS-ER ensemble mean, or an extrapolation of the AR-4 ensemble. In the interest of education, it would be great if you include the GISS model output after 2003 plotted to the same baseline as the Dominguez series (updated with the adjusted Argo data after 2003) and show this. I constructed a cursory plot of this myself, and the results are quite interesting. It looks like the models suggest an average radiative imbalance over the last 15 years that is significantly higher than indicated by the updated Dominguez series (please check). Regardless whether we look at Levitus or Dominguez though, the point remains that the next 5-10 years will be very telling on whether the models are accurately representing the net TOA radiative imbalance, especially since is becoming more clear that the decadal variablity is not as high as previously believed. Going forward, nearly all the individual realizations that I see never produce a single year without a significant gain of heat, short of a major volcanic eruption. I’m just hoping we don’t have another big eruption, since this would surely introduce some ambiguity into the picture.

    All who are interested, please look at figure 2 in Dominguez et al (2008) for more background. This is the plot that I have tried to update.

  20. 770
    Hank Roberts says:

    > davidmhoffer says: 6 January 2010 at 7:30 PM
    > … Oct 15, 1582. The day before that was Oct 4, 1582.

    “… September 2, 1752 was followed by September 14, 1752. The English people were furious at the change “give us back our 11 days” was the popular cry at the time.”
    http://www.the-kingdom.ie/news/story/?trs=cwaumh

  21. 771

    My, Tilo, you are a prolific poster, to be sure.

    Perhaps you can explain to me why you persist in arguing from first principles in the teeth of observations?

    Had you looked at some of the links given, you’d see that there is clear observational evidence that, indeed, multiyear (ie, thick) ice can decline quasi-independently of extent. So what’s the point of arguing it “can’t” happen? It can, and it has.

    More helpful–I mean, helpful to you–would be the question of where your logic fails. Certainly you’ve had a lot of folks trying to help you out. . .

  22. 772
    JCH says:

    Just curious. It appears to me the arctic has a lot of ice limiting shoreline. Hasn’t the ice extent record has been constrained versus the temperature record?

  23. 773
    Hank Roberts says:

    > the arctic has a lot of ice limiting shoreline.
    > Hasn’t the ice extent record has been constrained …

    Well, the Antarctic does too, in reverse, eh?

    Sea ice, fixed ice, grounded ice, icebergs, cap ice, thickness, age, density, composition — and I’m sure a real scientist can list far more things to watch.

  24. 774
    dhogaza says:

    Just curious. It appears to me the arctic has a lot of ice limiting shoreline. Hasn’t the ice extent record has been constrained versus the temperature record?

    It certainly limits the maximum winter extent. If you look at current maps, such as this one, you’ll see that the landlocked portions of the arctic sea are already frozen up to land.

  25. 775
    RaymondT says:

    Gavin, In the WCC3 presentation by Mojib Latif in Geneva last September he showed that hurricane activity and Sahel rain can be tracked to variations in Atlantic sea surface temperature. He then asked: how much of the decadal NAO variability is forced by changes in boundary conditions ? Since one of those boundary conditions is the radiative forcing due to an increase in CO2 my question is then how much influence does global warming due to CO2 increase have on NAO variability ?

    [Response: Do you mean NAO (North Atlantic Oscillation – defined as the pressure difference between Iceland and the Azores) or the AMO (Atlantic Multidecadal Oscillation – defined from the detrended Atlantic sea surface temperatue)? Depending on the answer, the response is different – there is some evidence that the NAO will move into a more positive phase (on average) in a higher CO2 world, for instance, The AMO is trickier since any departure from linearity in the response to all forcings will affect the AMO ‘index’ simply because of how it is derived. – gavin]

  26. 776
    RaymondT says:

    Gavin, Thanks for your reply. You mentionned that “there is some evidence that the North Atlantic Oscillation NAO will move to a more positive phase (on average) in a higher CO2 world”. Where could I find this evidence ? Thanks to your excellent web site I have been more and more convinced that the radiative forcing due to CO2 explains best SO FAR the trend in increasing global temperatures. I am less convinced however of the effect of the gentle ALTHOUGH PERSISTENT increase in global temperatures due to AGW on the occurence of extreme climate events. What is the link between the radiative forcing due to CO2 and the number and intensity of el-nino or la-nina events for example ?

  27. 777
    David B. Benson says:

    RaymondT (776) — Two papers in “Ocean Circulation and El Nino: new research” assert that global warming is likely to lead to more frequent El Nino events.

  28. 778
    Ernst K says:

    Monthly SOI index data:

    http://www.cgd.ucar.edu/cas/catalog/climind/SOI.signal.ascii

    It shows a weak, far from statistically significant, downward trend (El Nino events occur when the SOI is low).

    If you plot a 20 year+ moving average you’ll see that there was no trend at all until about the 1960s.

    CO2 radiative forcing, obviously, has a very strong statistically significant positive trend.

    Certainly interesting, but I wouldn’t hazard to anything stronger given all the noise in the SOI data.

  29. 779

    TR,

    Who the hell cares what it’s done since 2007? It’s 2010, TR, 3 years later. Go CHART the numbers I gave you and tell me whether it’s done anything similar before–and how many times. It jogs up and down. The TREND is still down.

  30. 780

    TR: The debate around the slope of the trend since 2008…

    BPL: Repeat after me:

    You need 30 years to find a climate TREND.
    You need 30 years to find a climate TREND.
    You need 30 years to find a climate TREND.

    Repeat it until it starts to sink in.

  31. 781

    Susan: Given the uncertainties in deriving the numbers you’ve provided by the university of illinois( the university certainly wasn’t collecting data on sea ice extent in 1870 or the earlier 1900’s was it, and to the same precision as satellite data?) Isn’t it safest scientifically speaking to say “Staying the same”?

    BPL: No. The “safest” thing to do scientifically is to go with the data. And whether the University of Illinois was collecting data on ice extent in 1870 or not, locals on land and sailors at sea certainly were. Do you think UI just pulled those numbers out of its blogs?

  32. 782
    Hank Roberts says:

    Googled:
    http://www.google.com/search?q=North+Atlantic+Oscillation+NAO+will+move+to+a+more+positive+phase+(on+average)+in+a+higher+CO2+world

    Found, among others, in the first page of results:

    http://insciences.org/article.php?article_id=1384
    (Appears to be a press release, or written from one)

    Illustration from Woods Hole:
    http://www.whoi.edu/page.do?pid=7545&tid=441&cid=85378&ct=61&article=54686

    “The research team found the variability of the NAO decade-to-decade (multi-decadal scale) has been larger, swinging more wildly, during the late twentieth century than in the early 1800s, suggesting that variability is linked to the mean temperature of the Northern Hemisphere. This confirms variability previously reported in past terrestrial reconstructions.

    “When the Industrial Revolution begins and atmospheric temperature becomes warmer, the NAO takes on a much stronger pattern in longer-term behavior,” said Goodkin. “That was suspected before in the instrumental records, but this is the first time it has been documented in records from both the ocean and the atmosphere.”

  33. 783
    RaymondT says:

    @777 David B Benson, 778 Ernt K and 782 Hank Roberts, Thanks for your replies. How frequent are El Nino and why ?

  34. 784
    Tilo Reber says:

    As much fun as it was talking to all of you, I decided to take a break and plot the RSS and UAH data from 1998, since they are now available to the end of 09. This gives us 12 full years. Here are the results.

    http://3.bp.blogspot.com/__VkzVMn3cHA/S0a9K-nTbYI/AAAAAAAAAFw/oWOaPsw2J6k/s1600-h/Twelve+Year+Satellite+Trend.bmp

    When skeptics say that it hasn’t warmed since 1998, this is what they mean. We can argue the significance, but we cannot argue the basis for their claim. By the way, for those of you who claim that it is due to the large El Nino at the start, look at the effect of the 2 year long La Nina that followed only 3 month after that El Nino. The effect on the slope by the two events is that they basically cancel each other out.

  35. 785
    CTG says:

    As much fun as it is watching you rebunking the “flat since 1998″ myth, Tilo, when will you stop cherry-picking and accept that these short-term trends are meaningless with respect to climate.

    Have a look at this.

    Three trends in the UAH data of exactly the same length, the only difference being the start and end date of each trend.

    Two are positive, one is negative. Which is the one that you claim is significant? Surprise, surprise – the one starting with 1998.

    Do you really think that if you just keep on endlessly repeating “the world has been cooling since 1998″ that it will magically come true?

  36. 786

    Kudos to Hank for the “The Brick Moon” reference!

  37. 787

    And here’s why Tilo’s #784 is wrong, something I’ve pointed out to him ever since he started with this claim long ago on Deltoid:

    http://BartonPaulLevenson.com/Reber.html

  38. 788
    Completely Fed Up says:

    “When skeptics say that it hasn’t warmed since 1998, this is what they mean.”

    You mean “according to the CRU data which the climategate emails PROVE has been falsified it hasn’t warmed since 1998″.

    According to other data, 2005 was warmer.

    And it’s false that it hasn’t warmed:

    2000 was warmer than 1999.
    mid 2005 warmer than mid 2004.
    early 2007 warmer than early 2006.
    2009 warmer than 2008.

    So its warmed many times since 1998.

  39. 789
    skeptic says:

    I wonder what that graph would look like with satellite temps (UAH & MSS).

    Just curious.

    [Response: They are different metrics, with different amounts of variability and I don’t have the relevant model results at hand. – gavin]

  40. 790
    Tilo Reber says:

    Barton:
    “And here’s why Tilo’s #784 is wrong, something I’ve pointed out to him ever since he started with this claim long ago on Deltoid:”

    Barton, have you noticed that it’s 2010 now?

  41. 791
    Tilo Reber says:

    GTC:

    Why would you not use the last available data in your choices?

    “Two are positive, one is negative. Which is the one that you claim is significant? Surprise, surprise – the one starting with 1998.”

    First of all, I’m not making 13 year claims, I’m making 12 year claims. So 97 is irrelevant to the claims that I’m making. I acknowledge that temperatures were rising until 1998.

    Second of all, three month after the 1998 El Nino ended a two year La Nina started. The effect of these two events on the slope was to cancel each other out. Your desire to start in 1999 just puts you at the beginning of the La Nina. And that is the only reason you get the positive slope. Last year the claim that people here made against the no warming scenario also included the fact that we had a La Nina in 2008. Well, that is over and we have added an El Nino year at the end – and still there is no warming.

    But really, the whole argument about choosing a starting point relative to a given ENSO event can be settled by using ENSO corrected data. I did that last year when Gavin produced an ENSO corrected data set. Here is the result:

    http://1.bp.blogspot.com/__VkzVMn3cHA/SHLOM1k5XJI/AAAAAAAAADE/u7AlyoBk0EU/s1600-h/ENSO+Adjusted+HadCrut3v+Data.bmp

    Take a close look at that chart. You can see how much the 98 temperature was reduced due to the ENSO correction. And yet the ENSO corrected trend was still relatively flat. Also, there was only a tiny difference between the ENSO corrected trend and the non corrected trend.

    It’s time to deal with the reality that the IPCC predicted rate of temperature rise should have been .24C over that 12 years and it is simply missing. And we don’t know why, since the level of CO2 has continued to rise as quickly as ever.

    One more thing GTC, positive and negative are not in themselves the issue. The issue is “where is the .24C positive?”

  42. 792
    Jim Eager says:

    Tilo Reber @784: I decided to take a break and plot the RSS and UAH data from 1998…

    Dense as a rock set in concrete.

    We know how septics get their “cooling since 1998″ meme, Tilo.

    We also know how wrong that meme is.

    [Response: More to the point it is extremely boring. Please no more on this. – gavin]

  43. 793
    Completely Fed Up says:

    Tilo: “It’s time to deal with the reality that the IPCC predicted rate of temperature rise should have been .24C over that 12 years and it is simply missing.”

    Please show where the IPCC reported that 12 years will see 0.24C warming.

  44. 794
    Hank Roberts says:

    RaymondT, you typed your question in the wrong little box.
    See the upper right corner of your web page? Where it says Search?

    Put your question there, and do it twice, once for searching the Site and once for searching the Web; it will look like this after you hit Enter:
    http://www.google.com/search?q=How+frequent+are+El+Nino+and+why

  45. 795
    Don Shor says:

    Completely Fed Up: Please show where the IPCC reported that 12 years will see 0.24C warming.
    From the 4th Assessment via Wikipedia: “A temperature rise of about 0.2 °C per decade is projected for the next two decades for all SRES scenarios.”
    I realize that is 2007.

    [Response: Before everyone else makes the same point, you do realise these are very different statements? – gavin]

  46. 796
    Steve Bloom says:

    Re #785 (CTG): I like “rebunking” very much and will use it. Re Tilo, I’ll predict that starting next year he’ll a) do a linear comparison of 1998 and 2010 to show that the temp increase isn’t statistically significant, and b) keep complaining that all the observations must be fraudulent and/or unreliable. If it’s a hot year to the point that a) doesn’t work, he’ll stick with b). Just sayin’.

  47. 797
    Completely Fed Up says:

    Hey, at least Tilo thinks that the CRU data is right: it has 98 as the hottest single year.

    So he hasn’t bought in to the CRU conspiracy “Climategate”.

  48. 798
    CTG says:

    Tilo asks “where is the .24C positive?”

    Here are the decadal average anomalies from GISTEMP:
    1880s -0.17
    1890s -0.3
    1900s -0.25
    1910s -0.21
    1920s -0.1
    1930s 0.01
    1940s 0.06
    1950s -0.02
    1960s -0.04
    1970s 0.02
    1980s 0.26
    1990s 0.39
    2000s 0.62

    So the 2000s are 0.23°C warmer than the 1990s.

    Does that answer your question, Tilo?

  49. 799
    Don Shor says:

    [Response: Before everyone else makes the same point, you do realise these are very different statements? – gavin]

    Statement one: the IPCC predicted rate of temperature rise should have been .24C over that 12 years
    IPCC report: A temperature rise of about 0.2 °C per decade is projected for the next two decades for all SRES scenarios.

    Yes, I realize they are not the same. “…should have been” is not a reasonable statement. I am assuming that the IPCC report was the source of the .2/decade estimate.
    I don’t think anyone has ever predicted that the temperature change will be linear. Is it accurate to say that the global temperature trend has been running at the lower end of the IPCC-reported SRES scenarios?

    [edit]

  50. 800
    Don Shor says:

    Anyone looking for a more detailed article about variations in temperature trend over decades may be interested in eduardo’s recent post at Van Storch’s web site: http://klimazwiebel.blogspot.com/2010/01/ten-years-of-solitude.html
    “Climate simulations show that decades of near zero or even negative global annual trends are not particularly unusual.”


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